In many video systems applications it is desirable to provide a changeable, controllable graphics display for viewing with a video display. Such applications include, for example, a film-to-video player wherein a photographic film is converted to a video signal for display on a video monitor. With such a film-to-video player, it is desirable to provide a graphics capability wherein such graphics icons as pointers and text can be displayed on the monitor with the video display. Such graphics can be used, for example, to highlight or identify a particular subject in the video display, or to provide text relevant to the video display. Many other uses are apparent to those familiar with such video systems.
It is often desirable to provide such graphics under control of a microprocessor, whereby great flexibility can be accorded in the forming and changing of the graphics icons and displays. Different texts, for example, can be programmed to appear with different video displays. Various icons can be displayed, and their positions moved. Further, various graphical displays, such as clocks and control information relevant to the video system itself, can be updated on a periodic basis.
In providing such a microprocessor controlled graphics display, the graphics system must be synchronized for operation with the video monitor--for example in accordance with standard, NTSC video timing. This requires that the graphics system be capable of operating at video speeds, which are often much faster than the speeds available from a microprocessor.